Method for and apparatus to extract a frequency reference, a time reference and data from a single information system

Abstract

A frequency reference, a time reference and data may be provided on, and subsequently extracted from, a single information stream. To achieve this a modulator 102 generates the single information stream by modulating the data on the frequency reference and pre-empting the data modulation to modulate the time reference on the frequency reference. This single information stream is then provided on a single bus 106 which is coupled to a plurality of base stations 103-105. The base stations 103-105 each include a demodulator 107-109, which recovers the frequency reference 117, the time reference 118, and/or the data 116, from the single information stream.

We claim: 
     
       1. A method for extracting a frequency reference, a time reference, and data from a single information stream, the method comprising the steps of: a) receiving the single information stream;   b) extracting, by a frequency decoder, the frequency reference from the single information stream independent from the time reference and the data;   c) extracting, by a time decoder, the time reference from the single information stream independent from the frequency reference and the data; and   d) extracting, by a data decoder, the data from the single information stream independent from the frequency reference and the time reference.   
     
     
       2. The method of claim 1, step (c) further comprising extracting the time reference by determining that a modulation of the single information stream is within a predetermined threshold. 
     
     
       3. The method of claim 2, step (c) further comprising determining that the modulation of the information stream is within a predetermined time threshold. 
     
     
       4. The method of claim 1, step (d) further comprising extracting the data by demodulating the single information stream. 
     
     
       5. The method of claim 4, step (d) further comprising pulse width demodulating a modulation of the single information stream. 
     
     
       6. A method for providing a frequency reference, a time reference, and data in a single information stream, the method comprising the steps of: a) receiving a frequency signal, a time signal, and a data stream;   b) modulating the data stream on the frequency signal, wherein modulation of the data stream is within predetermined data thresholds; and   c) preempting the modulation of the data stream on the frequency signal when modulating the time signal on the frequency signal, wherein modulation of the time signal is within a predetermined time threshold.   
     
     
       7. The method of claim 6, step (b) further comprising pulse width modulating the data stream on the frequency signal. 
     
     
       8. The method of claim 6, further comprising the step of extracting the data from the single information stream using a data decoder. 
     
     
       9. The method of claim 6, further comprising the step of extracting the frequency reference from the single information stream using a frequency decoder. 
     
     
       10. The method of claim 6, further comprising the step of extracting the time reference from the single information stream using a time decoder. 
     
     
       11. A reference system comprising: a receiver that receives a frequency reference signal, a time reference signal and data;   a modulator operably coupled to the receiver, wherein the modulator modulates the frequency reference signal, the time reference signal and data into a single information stream;   a plurality of demodulators coupled via a single bus to the modulator wherein each of the demodulators extract at least one of the frequency reference signal, the time reference signal and the data from the single information stream, wherein each of the frequency reference signal, the time reference signal and the data are extracted independently from each other by a respective one of the plurality of demodulators.   
     
     
       12. The reference system of claim 11, the modulator further comprising a pulse width modulator. 
     
     
       13. The reference system of claim 11, the single bus further comprising a coaxial cable.